/*
Generally speaking, scanf is faster than cin for reading formatted input
particularly when dealing with primitive data types like integers and floating-point numbers.
So cin in c++ is still usable
*/
#include<bits/stdc++.h>
using namespace std;
int n,cnt=0;
void stair(int pre,int forward)
{
    int cur=pre+forward;
    if(cur>n)return;
    if(cur==n)
    {
        cnt++;
        return;
    }
    stair(cur,1);
    stair(cur,2);
    return;
}
int main(){
    scanf("%d",&n);
    stair(0,1);
    stair(0,2);
    printf("%d\n",cnt);
    return 0;
}